Major quarantine and experimental vaccines to curb Ebola

The Ebola epidemic in West Africa is raging out of control. Known cases have topped 3000 – with the true number thought to be two to four times that – and they are climbing exponentially, doubling every 35 days (see diagram). The World Health Organization warns of a possible 20,000 known cases in the coming months if efforts to control the outbreak do not bear fruit.

The virus has now invaded Senegal, a fifth country, in what the WHO are calling a top-priority emergency.

The only effective controls are tracking and quarantining people exposed to the virus, and perhaps a vaccine. Last week, the WHO outlined an aggressive road map to stop the spread of the virus. It implied that this could involve quarantining entire communities in badly affected areas. An effort to do this without warning the community ended in riots in a slum in Monrovia, Liberia, last month, but the WHO hopes more community involvement will help in future.

An unprecedented effort has also been launched to make a currently experimental vaccine available on a large scale as early as January.

So far, quarantine has proved difficult. In July an infected man flew from Liberia to Lagos, Nigeria, and was hospitalised, infecting health staff. All people who had come into contact with him were thought to be isolated, but last week it emerged that one person flew to Port Harcourt, further along the coast, to be treated secretly. His doctor died and 160 people who were in contact with them are now in quarantine.

Under the radar

Meanwhile a man under surveillance in Guinea after exposure to Ebola travelled to Senegal and developed the disease. He initially went to hospital without warning medical staff of his exposure to the virus. The people he had contact with are now being traced.

Quarantine has worked on Ebola in the past, but those outbreaks had at most a few hundred cases. It is proving difficult to scale up such labour-intensive methods to the West African epidemic, says Bruce Aylward, head of emergency operations at the WHO.

"We can't contact-trace every individual," Aylward said in a WHO press conference to launch the new road map in Geneva, on 29 August. "So in this case you may have to trace an infected village or community for the time being." This implies that more communities could be held under quarantine.

The WHO's plan aims to stop viral transmission in the most affected countries by June 2015, and stop it invading new ones, for a projected cost of $490 million over the next six months. It calls for more Ebola treatment centres, healthcare facilities to find cases, contact-tracing and mobilisation of communities to safely bury people killed by Ebola, as well as the recruitment of 760 international health staff and 12,000 within the most-affected countries.

It also calls for "short-term extraordinary measures to limit national spread". While the road map doesn't spell out what the extraordinary measures are, it does call for healthcare, food and social support in containment areas. Aylward told the press conference the such measures should slow transmission in the worst hotspots enough by December to allow the standard method of tracking individual contacts of patients to become effective again.

Vaccine hope

The WHO plan emphasises cooperation with affected communities, for instance giving people more protective equipment so that they can care for their sick. But Aylward said unaffected countries are reacting to Ebola by buying up global supplies of masks, gowns and gloves, hindering the effort.

Even if they can be obtained, getting supplies and health workers into affected countries is getting harder. Airlines are cancelling flights partly because there are no certified safe hotels or medical care for air crews on overnight refuelling stops. The UN World Food Programme is supplying emergency aircraft to get people and supplies, and the WHO is in talks with airlines in a bid to fix these problems within a few weeks.

The other angle of attack is a vaccine. Last week UK-based pharmaceutical company GlaxoSmithKline said it would start making 10,000 doses of an experimental vaccine composed of a harmless adenovirus that expresses an Ebola protein. The vaccine was safe and provoked immune reactions to Ebola in tests in non-human primates, but had not been tested in humans.

Those tests will start this week with volunteers in the US, followed by people in the UK, Gambia and Mali. In an unprecedented move, GSK will make the vaccine in bulk while those tests are under way. If it passes, it could be used in Africa early next year.

Encouraging results have also been reported in primates with an experimental drug called ZMapp. But that drug is aimed at curing infected people and would have little impact on transmission of the virus.

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A medical worker outside an Ebola treatment centre at the government hospital in Kenema, in the east of Sierra Leone (Image: Meng Chenguang/Xinhua/Eyevine)